Transmission gearing for machine tools and other purposes



A R; w. J. FLETCHER TRANSMISSION GEARING FOR MACHINE TOOLS AND OTHER PURPOSES Filed. Jan. 11. 1923 I II 1; Z7 '1 3 Z7 l O )9 f 1 A9 i Z1 10 I a4 35 30 U \4 O i i 1 IL Q? 16 9;; l h O 1/ 19 \3 J- 8 I I 36 H Fi .5

' relating to transmission gearlng for machine -shall be particularly applicable Patented July 7,"

'uu rao STATES "PATENT orrica.

ROBERT w mm JOHNSTON FLETCHER, or EDINBURGH, SCOTLAND.

TRANSMISSION GEABING FOR MACHINE TOOLS AND OTHER PURPOSES.

Application filed January--11, 1923. Serial No. 611,955.

To all whom z'tmciy concern:

Be it known that I, RoBER'r WILLIAM J oHNsT'oN FLn'roHnn, a subject of the King of England, residing at Edinburgh, Midlothian, Scotland, have invented certain new and useful Improvements in Transmission Gearing for Machine Tools and Other Purposes, of which the following is a specification.

This invention is for improvements in or tools and other purposes and has for one of its objects to provide a construction whlch to power driven screw drivers and drills. It is to be understood, however, that various features I of the invention are also applicable to other types of machine tools and machinery.

It is useful to drive a power driven screw driver bya flexible shaft in order to permit the screw driver to-be shifte'd'about around an, article which is having the screws driven into it. A difiiculty. which hasbeen experienced, however, is that the speed at which the screw driver should be rotated is very much less t an the most efficient speed at which to drive the flexible shaft. Another requisite in these tools is that when the screw has been drivensufii'ciently far home the rotation of the screw driver may readily .;be discontinued so as not to damage the screw. It will be appreciated"fthat these difficulties and requisities also apply more or less toother types of machine tools such as drills, grinders, tapping tools and the like, with the difference that in certain of g the tools, notably drills for-metal and grinders, the speed of the tool can be maintained:

much higher, than can the speed of a screw driver. Hence in some cases an increase rather than a reduction in speed may be required. 1

According to the primary feature, of the present invention there is provided in or for ical' planet rollers loosely carried in a' cage to' rotate about the sun roller, and a' 00- I operating conical surface enclosing the planet rollers, said planet rollers being only pressed into operative driving engagement with the sun roller and the said co-operating surface when the tool is pressed against itswork. The sun roller and planet cage may be connected one to each of the main shaft and the tool or like carrier driven thereby, and the aforesaid co-operating 'conical surface may be connected to a handle 7 whereby the gearing and carrier are manip ulated. 1

For a more complete understanding ofthe invention there will now be described, by way of exampleonly and with reference to the accompanying drawings, certain constructional forms of the transmission gearingaccording to the invention. It is to be understood, however, that the invention is not limited to the preciseconstructional details set forth.

In these drawings Figure 1 is anelevation, part1 in section,

of a construction of gearing w ich is particularly applicable to a screw driver driven by' a flexible shaft.

Figure 2 is a sectibn on the line 22 of Figure 1, and 1 Figure 3 isa View correspondingto Figure 1 of a modified construction in which a drill is shown as being driven from a rigid shaft at a greater speed than the latter.

parts throughout the drawings. 1

Like reference numerals indicate like Referring firstlyto Figures '1 and 2, t

flexible shaft is indicated at 10 anda screw driver at 11, the latter being received 'in' a suitable carrier 12. Above the carrier is a casing 13 to which is secured a handle 14 b which'the tool is held and manipulated? Projecting down through the handle and casing is the end 15 of the flexible shaft and this carries at its end a sun friction roller 16.0f conical formation. of this roller and the adjacent face of they casing 13 is a thrust bearing 17. Inside the casing 13 is an internally coned member 18 which is mounted in place by suitable screws 19 and which is received on a bearing 20 rotating with the tool holder 12. Lying between the roller 16 andthe conical member 4 18is a cage 21 made in one piece in which three conical planet rollers 22 are mounted.

These rollers have projecting ends 23 which Between the head i agre loosely received in radial recesses" or slots 24= in thetw'o ends of the cage 21, which recesses or slots are open at the periphery of the cage to permit the planet-rollers to be removed from the cage by bodily move-'- ment thereof, in a direction at right angles to their axes. Theroller 16 is preferably also provided with an extension 25 which is centred in the cage 21. Thecage-21 is con.- nected t'o' the carrier 12 through a member 26. Itwill be observed that the screws 19 are received inelongatedholes 27 in the casing 13 so that a certain-amount of movement.

is permittedbetween'themembers 13 and 18. n operation it will be seen that the flexible shaft 10 will rotate the sun rolldr 16 which willdrive the planet rollers 22 about their own axes. Since these rollers will be bearing upon thesurface 18, however, they will be caused to travel along the latter and thus will drive the cage 21 and the screw driver 11 which is carried thereby. The casing 13 will be held stationary by the handle 14. The operator will bear upon the handle 14 to force the point of the screw driver into the head of the screw and as long as he is exerting this pressure the sun roller 16 will be forced into driving engagement with the planet rollers and the latter into similar engagement with the member 18 Whenever, however, the operator relaxes his pressure the rollers will be free to slip. Therefore, when this is done rotation of the screw driver 11 will cease even though the shaft 10 still continues to rotate. This slipping will be facilitatedby the loose mounting of the' rollers 22 and by the freedom of the member 18 to move relatively to the casing 13'; moreover these arrangements just described also permit of an effective clutching action to be 1 secured when necessary, since they. permit the rollers-to shift radially and seat themselves correctly in position despite any wear "which may have occurred. It will bee preciated that the speed at which the screw 'driverj'will be driven will be less thanthat .pf the driving; shaft 10 by reason of the fepicyclic rollers. I i By'reference to Figure '3 it will be seen that the invention can also be applied to machine tools or the like in which the drive is taken from a rigid shaft 28 and is transmittedto a tool 29 through gearing which multiplies the speed instead of reducing it as shown in the construction in Figures 1 and 2. In the construction shown in Figure 3, the tool carrier 12 is connected to a sun roller30 while a planet cage 31 is connected. to a member 32 Which is driven by the shaft 28 but can be slid longitudinally thereof by the adjusting vhandle 33 operating sayv through a rack and 'piniomnot illustrated.

The planet rollers 34:,- are loosely mounted in radial slots in thecage 31 and are reversed in direction as compared with the sun roller esitate I 30. The co-operating conical surface 35 is carried 1n a stationary casing tit-by: screws- 19 entering into elongated slots 27' as shown in the construction in Fi ures-1 and 2. A

thrust bearing 37 is provided in .the casing 36 and in the head of the roller 30. The casing 36 isheld stationary by any suitable means, such as a projection 33 adapted to bear against some stationary part of the Ina-l chine; or the casing could beheld stationary by hand: 1

In the constructionshown in Figure 3, the

planet cage 31 is, driven by the shaft 28 their axes by reason of the engagement with and, its rollers being caused to rotate about the member 35, drives the sun, roller 30 and consequently also the tool -29 ata speed I higher than that of the shaft 28. The auto- I mat-ic d'eclutching of therollers already de scribed in connection with Figures land 2 is also obtained in the construction shown in Figure 3. In both of the constructions illustrated, the end of the driving shaft 10 or ,18 attached to the tool is in alignment with the longitudinal axis of the topl, Which is found to be a very convenient arrangement,

as the driving shaft is wellout of the w y f the operator.

It is to be understood that the'invention is i not limited to the precise constructional details hereinbefore set forth. or example, a number of" planet rollers otherthan three maybe employed, and the ratio of the speed of the driving to thedriven member may be varied both up andfldown according to cir cumstances by suitably designing the rollers.

I claim 1. In self-adjusting friction gearing, the combination of a conical sunvroller, conical planet rollers surrounding the same and fixw edly carrying each a pivot-pin at each end,

a conical abutment surrounding and making contact with said planet-rollers at their peripheries, and a one-piece cage having ra; dially directed slots into which said pivotpins extend, which slots ermit movement of the planet-rollers bodily towards and away from said sun-roller in a radial direc- ,tion, but always maintain constant the angle at which the planet-rollers are spaced apart around the sun-roller whatever radial posi tions they may take up, said sunroller and cage being relatively movable axially of the towards and away from said sun-roller and permit removal of said planet-rollers from said cage by a bodily movement thereof in a direction at right angles to their axes, said sun-roller and cage being relatively movable axially of the sun-roller, substantially as described.

3. In a portable machine-tool, a casing, a shaft journaled' therein, a conical sun roller carried by said shaft within said casing, a

member fitted in said casing and having a L conical friction surface, said member being held against rotation relative to said casing movement of the planet-rollers bodily towards and away "from said sun-roller, said sun-roller and cage being relatively movable axially of the sun-roller, substantially as described. I

4. Friction gearing having a driving shaft, a driven shaft and a casing, a conical sunroller fixedly connected to one of said; shafts,

a cage fixedly connected to the other shaft, a

conical bearing surface in the casing; adapt ed to move longitudinally thereof but heldv against rotation relative to the casing, and conical rollers in the cage adapted to move longitudinally therewith and in rolling contact with the sun roller and the bearing surface, the arrangement being such that when pressure is applied to one of the shafts to move it longitudinally relative to the other I the rollers will bemoved into driving relation with the sun roller andthe bearing sur:

'face to drive the driven shaft, substantially as described. r

3 In testimony whereof I have signed my name to thisspecification in the presence of two subscribing witnesses.- I

ROBERT WlLLlAM JOHNSTON FLETCHER.

Witnesses: 7

Tnos J. MULnAnY, J ESSIE P. BATOHEIDR. 

